Okay, it's 2am and i can't sleep so mind goes wandering The thread on free boat engines started something--so here goes. What does it take to reverse and engine's rotation direction? I think I've heard that the cam would need to be ground differently and the oil pump probably would need some work but what else? Any reason it wouldn't make as much power running that way as the normal way? It's a weird idea and I want to work on it a while to see if what I got in mind is doable
Yea,it should make the same horsepower. I read quite awhile ago that an early stock-car builder ( Smokey Yunick ?) made up an engine to reverse rotation, to try to get better traction on turns for dirt-track use.
I know the feeling, I cook up crazy, impractical ideas all the time. I'm working on one right now. Back to your question, I've never done it, but I can't think of any reason you would make less power. The first, most obvious thing that comes to mind in spinnning the accessories the right way. Also, not quite sure how it would affect the way the power was applied to the distributor gear. As for the cam, what if you just ran a 2-gear timing system? That way the cam would run the opposite way.
I've read about them being tried in oval racing. One of the problems is the fact that the coolant flow is reversed. The engine doesn't cool as efficiently with flow entering the top and exiting the bottom. Also, once you have the rotation reversed, then you need to switch it back or you'll have four speeds in reverse and just one in forward. Evidently the way that's been handled was to put the rearend in the car upside down. Hard to accomplish with a quickchange though.
I've reversed the rotation on small Fiat engines a lot. ( Because the bigger version of the same family of engines ran the other way ) The wrist pin was slightly offset in the piston ( they do that to make sure there is no piston slap...), so you had to turn the pistons 180 deg in the bores. And the engine needed a different cam, and the little driveshaft that went between the oilpump and the distributor. ( the gear on it meshed with a gear on the cam ) Switching that little driveshaft with the cam made the oilpump & distributor run in the same direction as before... Then it also needed a waterpump & alt or generator that ran the right way ( alt might work either way, but the cooling fins next to the pulley will be pointed the wrong way.) But I think on some engines they dont offset the wristpin in the piston, but offset the crank a little from the centerline of the cylinder bore. I think if you'd run one of those backwards you'd loose power...
pretty sure that with the reverse rotation you lose power becuase of how heads are designed (intake and exhaust valves being differant sizes). There is a vid on youtube of a rod running this style engine setup.
you'd definately need to build the cam to match valve timing in going opposite direction. water pump and oil pump would be screwed, as would transmission, etc.... gives me a headache to think about -scott noteboom
If you are talking about a SBC marine engine, you just need to put in a standard rotation cam, distributor and water pump. I think the oil pump also, but can't remember for sure. The block, heads, crank, rods, pistons, intake, timing set, tin and flywheel are all the same. Move the timing pointer to the opposite side of TDC. Alternators don't care.
I believe that there have been twin engine marine applications where one engine turned the opposite direction from the other. This was to make the boat go straighter. Check out the marine engines if this is keeping you up at night. Sweet dreams.
Yah, a standard Mercruiser Marine engine is reverse rotation. It is so the torque will keep the right hand seated driver 's elbow out of the water,heh... The starter is of regular rotation, but is plugged in from the rear of the bellhousing. It uses a 2 gear drive on a standard ground camshaft to reverse it and regular disty. (You could use a gear drive ground cam with a roller chain too) Have heard but cant confirm that the "mercruiser" crank has the oil holes drilled in a different place to time the oil squirts at the rod bearings for rev. rotation. (Old boat mechanic) MIZ
easy to do the hard thing is coming up with a tranny//i know some circle track guys used o run reverse rotation engines back in the 60's
All twin engine inboard boats run the engines in opposite rotation of each other to equalize the torque from the props. To convert the one back to standard automotive rotation just use automotive cam , pump, ect. No big deal. Remember they are not reverse flow, just reverse rotation, no power loss.
Ive heard of Nailhead COnversions for Corvairs that had to reverse Rotation, or maybe that was the 215 Nailhead?
Many of the early multiple engine dragsters would place two motors side by side and mesh the ring gears. They would run one engine foward rotation and the other in reverse rotation. They would then place the tranny on the standard rotation motor. Result: twice the HP delivered to the tranny. As far ar the building a reverse rotation engine, I believe there is a guy that runs one, or at least had on at the earlier Hunnert shows. He had eight side-draft carbs mounted in the exhaust ports and straight stacks out the intake ports. http://www.hunnertcarpileup.com/2005_pics/hcpu05_312.jpg http://www.hunnertcarpileup.com/2005_pics/hcpu05_313.jpg http://www.hunnertcarpileup.com/2005_pics/hcpu05_314.jpg http://www.hunnertcarpileup.com/2005_pics/hcpu05_315.jpg
Worked with a dirt tracker once to build a 240 ford run rev. rotation. It was pretty simple. Just turned the cam end for end ( center diz.)and put a chain drive on it. As for the rear end, had to flip the ring gear. Other wise would have needed a LARGE rear view mirror. It worked great, but you had to stay on the loud petal in the turns or it wanted to make right turns if you lifted.
Some reverse rotation motors have the cranks knurled for that rotation only. Running them backwards they will leak oil at the front & rear seals. Whether yours does I cant say, but its someting you might want to check on before doing a lot of work on it
I've seen some ratrods with the intake and exhaust locations switched, but they weren't reverse rotation.
http://www.autohistory.org/feature_1.html check this out, reverse rotation, reverse flow, upside down V8-60 engine in a midget sprint car. Talk about inovation!
I also have a boat so here is how it is done(on a chris craft anyhow) you need a different cam, you get rid of the timing chain&gears and they are replaced with two timing gears,the crank gear spins the cam gear(nope not like a gear set from summit) just two gears. now you have to get a starter to spins backwards, They use the same dizzys,water pumps,fuel pumps you need to replace the oil seals on the crank or they leak like h**l,I tried I know. A marine motor has different head gaskets,but you can run them in cars,but not car gaskets in boats. The carbs have the fuel vents dumping back in the top of the carbs, I hope this helps a little Russ
Gas golf carts don't have transmissions they have a gas motor and a starter. Depending on which way u wish to go, that is the way it starts the motor. The motor runs in both directions. Totally cool shit.
lets get this clear, reverse rotation means the crankshaft spins the opposite direction. reverse indcution means the intake and exhaust switched.
Yep, they tried this with Bill Slater's "V8" many years ago. That car had a Ford rear but it had to be flipped. I'm not certain that the car had that much more left rear bite to go to the trouble, but it screwed with Ed Flemke's head.... Jan
It's easy with a quick change, put the ring gear on the right side of the pinion gear, make reversed impellers for the water pumps, mag or distributer is gonna go the oppisite way, mechanical fuel pump will too, have seen a few in Sprint Cars and Midgets, never drove one but it didn't seem to make a huge difference
Thats funny I used to go to the races at Lakeside as a kid. Yes there are still some old sprint/midget cars around that area. But, now the track is just a cracked up old piece of shit.
I am scheduled to get those twin 327s next weekend out of that boat. I'll post here or a new thread on all the differences I can find between the two.
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